A polyurethane material is a polymer having a repeating structural unit of a carbamic acid ester segment made by an isocyanate reacts with a polyol. Wherein, the international market of isocyanate tends to be stable, mainly MDI and TDI two types, supply and demand tends to balance and the production process is relatively perfect; and polyurethane polyol variety, currently on the market dominated polyols mainly for the high functionality polyether polyol obtained by reacting a hydroxy compound and an amine compound with epoxy propane or ethylene oxide, in addition, there are polyester polyol, modified graft polyether polyol and so on, and these polyol products are the downstream products of oil, resource dependence is strong, prices is high, process safety is poor. Therefore, it is an important trend for developing bio-based raw materials to substitute petrochemical resources, develop bio-based polyols, improve product quality, reduce resource dependence and improve process safety.
Vegetable oil polyol is an important renewable resource, it can react with isocyanates compound and produce polyurethane, it is a good alternative of petroleum-based polyol raw materials. In recent years, methods of synthetic vegetable oil polyols are: 1) alcoholysis the vegetable oil and polyol, produce polyhydroxy compound; 2) oxidation unsaturated double bond of vegetable oil by using ozone, produce polyhydroxy compound of hydroxyl group which contain end position. 3) oxidizing the vegetable oil to an epoxy vegetable oil and then producing polyhydroxy compound by hydrolysis, hydrogenation, methyl esterification or halogenation.
The synthetic vegetable oil polyol process, method 3) which is the epoxy ring opening method for the preparation of vegetable oil polyol is low cost, is currently recognized as the most likely in the polyurethane industry to achieve the industrialization method, and usually combined with the method 1). CN1837180A and CN101139252A, respectively, using rapeseed oil and jatropha oil as main raw materials to prepare the vegetable oil polyol by alcoholysis/epoxidation/ring-opening three steps reaction. CN1837181A and CN101108803A, respectively, using rapeseed oil and jatropha oil as main raw materials to prepare the vegetable oil polyol by epoxidation/ring opening/alcoholysis three steps reaction. CN1907944A epoxidized rapeseed oil is used as the main raw material, and the vegetable oil polyol is prepared by the two steps reaction of ring opening and alcoholysis. CN 101314632A discloses “a method for the preparation of rigid polyurethane foams by using soybean oil”, which comprises four steps, which are epoxidation/ring opening/alcoholysis/esterification. CN101906016A discloses “a rubber seed oil polyol and a preparation method thereof”, the rubber seed oil is used as the main raw material to obtain the vegetable oil polyol through the epoxidation/ring-opening two steps reaction. CN102206154A discloses “a vegetable oil polyol and method for the preparation thereo”, including epoxidation and ring-opening two steps reaction.
The patented preparation of vegetable oil polyols are synthesized through batch reactor, epoxidation and open-loop is divided into two steps, there are the following disadvantages: {circle around (1)} long reaction time; {circle around (2)} high energy consumption; {circle around (3)} low level of equipment and automatic control; {circle around (4)} Unavoidable side effects lead to lower product quality (oligomerization side effects lead to low hydroxyl value of the product, the viscosity is too large).
In addition, the product of the vegetable oil polyols based on epoxidized/open-ring and even epoxidized/open-ring/alcoholysis or alcoholysis/epoxidation/ring-opening reaction are still common low hydroxyl value, quality is not high, when using for polyurethane materials, a certain percentage of petrochemical-based polyols are still needed.
Based on the said problems, the present invention overcomes the shortcomings of the prior art, designs a new synthetic route and combines the new production technology to synthesize a vegetable oil polyol, which are novel structure and high quality, can completely replace the traditional petrochemical base polyol and apply in the polyurethane foam materials.